A-level Chemistry Essay

- s and p bonds; electron clouds; bond polarity; difference in EN; I-effect; M-effect; delocalization of p electrons; electrophiles; nucleophiles;

- A_N reaction with general mechanism

- Relative reactivity

- Addition of HCN and NaHSO₃

- A_E reaction with general mechanism

- Relative reactivity

- Addition of HBr and Br₂

Characteristics of >C=O

2. The unhydridized p-orbitals of C-atom overlaps with a p-orbital of O-atom to form a p-bond.

2. Two negatively charged p-electron clouds lie above and below the plane of atoms.

	Carbonyl group (C=O )	C=C double bond (C=C)
Structure / Shape	C-atom undergoes sp2 hybridization and it is trigonal planar.	C-atom undergoes sp2 hybridization and it is trigonal planar.
Bonding	s and p bond Because of the presence of unsaturated bond, it undergoes addition.	s and p bond Because of the presence of unsaturated bond, it undergoes addition.
Polarity	C=O bond is polar. Oxygen is more electronegative and withdraws electron density by I & M-effect	C=C bond is non-polar.
Typical reaction	Nucleophilic addition (AN) The positive carbonyl carbon will attract nucleophiles (e.g. CN-) and it undergoes nucleophilic addition.	Electrophilic addition (AE) The negative p electron clouds above and below the double bond will attract electrophiles (e.g. H+) and undergoes electrophilic addition.

II Typical reactions of carbonyl compounds (3 marks)

Because the carbonyl group (>C=O) is planar, this part of the molecule is